Here are the house rules I use for a d12 system:
Cavalry attack at 1, defend at 1, and move 2. On land, they may Entrench. (I use Der Kunstler’s entrenchment rules.)
Cavalry may blitz. You know what that is. They may also use the Charge! feature, which means they attack at 3 if the number of attacking cavalry is greater than or equal to the number of defending light, regular, or colonial infantry. Cavalry have the Flank! feature, which means that if a player has cavalry units in an attack and an opponent has no defending cavalry, the attacker can roll an extra die during the first cycle of combat. Finally, cavalry may use the Retreat! feature, which means they may choose to retreat after each completed cycle of combat rather than stay and fight. On the attack, if paired 1:1 with Artillery, cavalry may attack at 2. Cavalry cost 3 IPP.
Armored cars attack at 2, defend at 2, and move 2. Armored cars may blitz, flank, and retreat. They also have the Reconnaissance feature, which allows them to pair with artillery on a 1:1 basis to re-roll one die during each cycle of combat. Armored Cars cost 5 IPP.